Conversion of hydrocarbons



Patented July 18,1939 1 v 2,166,544 I UNITED srATEsrATE-NT OFFICE CONVERSION OF HYDBOCARB ONS Thomas Cross, In, Baton'Bouge,.La., assignor to Standard Oil Development Company,v a corporation of Delaware No Drawing. Application December 17, 1935,

' Serial n 54,961

3 Claims. (01. ran-5o) The present application relates to the producand results in a highly adsorptive or absorptive tion of motor fuel of improved octane number, product. The aluminum hydrate is preferably and is specifically directed to a catalytic process alumina scale deposited from sodium aluminate forreforming naphtha whereby improvements in solutions in the form of scale in the aluminum 5 octane number 'canbe achieved witha minimum precipitating tanks employed in the well known 5 gas loss. Fickes-Sherwin modification of the Bayer proc-- It is known that the octane number of naphtha, ess, in which aluminum oxide is precipitated from particularly straight'run naphtha, can be im-' sodium aluminate. The term activated alumina proved by: subjecting the naphtha to high temas herein employed, is here defined to mean calperature treatments, the purpose of which is to cined alumina produced by calcining aluminum 10 increase the content of lightends in the naphtha hydrate at temperatures from 300 to 800 C. and/or rearrange the molecular structure. of some and to no other materials. Another especially of the constituents of the naphtha. In processes desirable activated aluminous material for use of the latter type the naphtha is usually conin the present invention is a clay known as ducted in the vapor phase over a dehydrogena- Marsil clay activated according to the process 15 tion catalyst at atmospheric, slightly elevated described in French Patent 760,646 published or reduced pressure at a temperature between February 27, 1934. This clay contains from 5 1000 and 1150 F. 'While this treatment does to 17% of alumina. Activated alumina contains. improve the octane number of the naphtha, it 91.23% alumina, The content of alumina is not,

90 causes the production of relatively largewolumes however, determinative of the utility of the 20 of gas which consist, to a very substantial exaluminous material for the present invention tent, of hydrogen and. fixed gases of the olefinic since Attapulgus clay containing 16.5% of aluand paraflinic type. The extent of this gas loss mina, Terrana containing 54% of alumina appears to bear a linear relation to the degree of and pumice stone, containing a large per-- improvement in octane number up to an improvecentage of alumina in combination with silica, 25 ment to about 70 from a stockhaving an initial have been found to be unsuitable for use in the octane numberbelow '70, after which the gas loss process of the present invention. I rises steeply for each increment in octane number. According to the present invention a naphtha A It has now been discovered that certain actiis passed in the vapor phase over the activated vated aluminous materials influence the reformaaluminous material at a temperature between 30 tion of naphthas in a remarkable manner. These 900 and 1050 F., preferably at about 980 F. materials make possible the reformation of The greatest benefit is derivedfrom the present naphtha at lower temperatures than those per-. invention when the improvement desired in the missible for reformation with dehydrogenation octane number of the naphtha is only moderate.

5 catalysts of the usual type,;with much lower In such cases the desired improvement can be gas losses, particularly when the. desired final obtained by contact with the activated aluminous octane number of .the naphtha is not too high, material with a far smaller gas loss than that inthat is, is not over 70. In addition, when these curred for the same octane number improvementmaterials are .employed as contact agents, the when other contact agents are employed. low,molecular hydrocarbons split oil from the As an illustration of the difierence in. effect 40 naphtha contain large percentages of butanes between an activated aluminous material and an and relatively small amounts of hydrogen, norunactivated aluminous material, the following remally gaseous paraffins and olefins. In short, sults of two experiments are offered: A heavy these activated aluminous materials appear to naphtha derived from a crude originating in exercise a fairly positive control over the point West Texas and having an octane number of 4'7 45 at which splitting of the initial hydrocarbons C. F. R. was passed at atemperature .mainoccurs. 1 tained substantially constant at 1050 F. over uni A very suitable activated aluminous material treated Attapulgus clay, the feed rate being befor use according to thepresent invention is the tween 350 and 500 cc. of naphtha per 340. cc. of

0 activated alumina described in Patent No. clay per hour. The gas obtained had a density of 5 1,985,204.. According to this patent, the activated 0.52 and the gas loss amounted .to 4.15% by alumina is prepared by calcining aluminum hyweight. The octane number of the product was drate at a temperature between 300 and 800 0., C. F. R.

preferably at about 350 C. The calcination of The same initial material w as passed over acaluminum hydrate causes a partial dehydration tivated alumina at a temperature of 950 F. and 55 at substantially the same rate of flow. The gas given oil had a density of 0.785 and the gas loss amounted to 1.2% by weight of the initial material. The octane number of the product obtained was 57.5. v The same initial material was passed over Marsil clay at a. temperature of 1000 F. and at substantially the same feed rate. The gas recovered had a density of 0.725 and the gas loss was 2 .5% by weight. The octane number of the product obtained was.55.5.

In comparing the effect of aluminous material with a dehydrogenation catalyst, a West Texas heavy naphtha having a C. F. R.MM octane number of 41.5 was used as the initial material. Activated alumina was employed in the first run and a catalystcomposed of the oxides of chromium, zinc and lead deposited on magnesite was employed as the catalyst in the second run. In each run the feed rate was the same. In the first run at 970 F. a gas loss of 6.3 was incurred and in the second run at 1060 F. a gas loss of 6.15 was incurred. The product in the first run had an octane number of 65.5. The product of the second run had an octane number of 63.5. One cc. of lead increased the octane number of the first productto 74.5 and the octane number of the second product to 70.3. Two cc. of lead increased the octane number of the first product to 77.2 and the octane number of the second product to 73.7. The sulfur content of the first product, was 0.037 and that of the second product was 0.079. In a bomb breakdown test both products broke down in 18 minutes. The addition of 10 milligrams of alpha-naphthol per 100 cc. to the first product increased the breakdown time to 72 minutes. The same addition to the second product increased the breakdown time to only 24 minutes.

In order to illustrate that the effect of the activated aluminous material was more than that of a medium for causing turbulence, several runs were conducted in which a West Texas heavy naphtha having. an octane number of 47 was passed at the same feed rate over activated alumina, pumice and iron jack chain respectively. In one run over activated alumina. at 1000 F. the conversion was carried to a. 3.65% gas loss and yielded a product having an octane number of 63.5. In duplicating this octane number increase over pumice a gas loss of 6.15 was incurred, and a temperature of 1080 F. was required. The same octane number increase was obtained over iron jack chain with a gas loss of 6.85% and only at a temperature of 1090 F. In obtaining an improvement in the octane number of the West Texas heavy naphtha to 63.5 with a dehydrogenation catalyst of the type described above, the gas loss incurred was 4.7%.

In a run over pumice at 1075 F., in which the conversion was carried to a 9.4% gas loss, the octane number was increased to 65 at a feed rate the activated' 2,168,544 U v of 115 cc./hr. In madman overactmtd alumina at 1040" F., in which the conversion was carried to an 8.5% gas loss, the octane number was increased to 71 with a feed rate of 210 cc./hr. In a similar run over Marsil clay at 1040 F., the octane number was increased to 66 with a gas loss of 5.5% with a feed rate of 300 cc./hr.

When the conversion was conducted in-the presence of activated alumina to ages loss of only 1.2% the octane number was increased to 57.5. With a gas loss of only 1.5% over Marsil clay the octane number of the product obtained was 59.5. A conversion to a similar gas loss over pumice stone made no measurable difierence in the octane number. It was found to be very diflicult to restrict-the gas loss over pumice stone to such a small value, since with this material there appeared to be no middle course between a conversionto a high gas loss and no conversion at all. When Attapulgus clay was used as the contact material at a temperature of about 1050 F., or slightly higher, the gas loss incurred was 6.4% and the octane number .of the reformed West Texas naphtha was 57, or belowv that ob tained at a gas loss slightly above 1% with the activated aluminous material.

In the above examples the rate offeed of naphtha indicates liquid measure. Heat may be supplied to the reaction in any conventional manner. The reaction tube may be immersed in a bath of molten metal or imbedded in a metal block, such as a bronze block, heated electrically. For preheating the naphthaa conventional coil heater is employed.

In the specification and claims where reference is made to v/v/hr. it is to be understood that this has reference to the units of volume of the feed stock per unit of volume of the catalyst passing thru the reactor perhour.

The nature and objects of the present invention having been described and specific illustrations of the character of the improvement eiIected thereby having been given, what is claimed as new and useful and desired to be secured by Letters Patent is:

1. A process for improving the octane number of a heavy naphtha which comprises subjecting said naphtha in'the vapor state at a temperature between about 900 and about 1050 F. to the action of an activated Marsil clay.

2. A process as in claim 1 wherein the activated Marsil clay contains between about 5 and about 17% activated alumina.

3. A process for increasing the octane number of a naphtha, which comprises subjecting said naphtha in the vapor state at a temperature between about 900 and about 1050 F. to the action of an activated Marsil clay at a thruput of between about 0.88 v. and about 1.47 v/v/hr. measured while liquid. 

